This invention relates to an ion source application device and in particular to an ion source application device used in an ion beam etching device, an ion implantation device, a neutral beam injector, etc.
Recently ion beams have been widely utilized for fabrication and working of semiconductor devices and functional thin films (e.g. films for the magnetic head). For example an ion beam etching device using microwaves has been proposed in JP-A-59-46748 as a dry etching device, which is indispensable for fabricating so-called submicron devices. The dry etching is a method, by which gas plasma or ion beam is used for etching, contrarily to the etching of a semiconductor surface by means of liquid. When such a device is used, high precision etching is possible. At the same time, even in the case where oxygene or reactive gas such as fluorine, chlorine, etc. is used, it gives rise to no problem that a filament is consumed as in an etching device, in which an electron bombardment type ion source is used, and has an advantage to stand a long time use. However, since this device produces plasma by using the electron cyclotron resonance (ECR), it is difficult to obtain a uniform ion beam in a wide region and therefore it is not suitable for an application, in which a number of wafers are treated simultaneously.
On the other hand Lawrence Berkeley Laboratory in U.S.A. has developed a high frequency ion source as an ion source used in a neutral beam injector for the nuclear fusion and succeeded to obtain a hydrogene ion beam having a uniform intensity over 100 mm.times.100 mm. This is reported in "Radio Frequency Ion Source Development for Neutral Beam Applications" (K. N. Leung et al., J. Vac. Sci. Technol. A2(2), Apr.-June 1984). When this ion source is applied to the etching device stated above, advantages are obtained that an ion beam, which is uniform over a wide region, is obtainable and at the same time that it can be stably driven during a long period of time as compared with an electron bombardment type ion source even in a reactive gas for generating high frequency discharge at the plasma production.
However, although the ion source developed by Berkeley Laboratory described above utilizes high frequency discharge, electrons serving as seeds for starting it are obtained by lightening a filament during a short time at the beginning of the discharge. Therefore it has a problem that the life of the ion source is shortened by the consumption of the filament.